California’s largest state employee union fell victim to a ransomware attack last month that, according to a cybersecurity analyst, likely exposed Social Security numbers, home addresses, birth dates and other sensitive information. The union, which represents close to 96,000 California state workers, first reported news of a “network disruption” on Jan. 20, two days after the breach occurred. At the time, SEIU Local 1000 told members that it was “currently assessing what was affected.” An update released Monday evening in the form of an open letter confirmed the breach, but offered few detail…